Groyne

About: Groyne is a research topic. Over the lifetime, 397 publications have been published within this topic receiving 4549 citations. The topic is also known as: groin & Breakwater.

Flow analysis around groyne with different permeability in compound channel floodplains

Abstract: Presented herein are the results of an experimental study on the flow characteristics around compound channel floodplain groynes with various permeability and length. Both the permeable and impermeable groynes are considered to clarify the influences of floodplain groynes on flow structure, velocity, and water surface. A channel consisting of a main channel and one floodplain with flat and fixed bed was used. The width of floodplain is the same as the main channel width. Pile groyne models with three different relative lengths relative to floodplain width (Lr), 0.5, 0.75, and 1.0, with three different permeability values (P= area of water crossing the groyne/total projected area of groyne) 40%, 60%, 80% plus an impermeable groyne were used and installed in the floodplain with single arrangement. The 3D flow velocities at both of the horizontal plane above floodplain bed by 0.25 of floodplain water depth (h) and at the main channel centerline in the vertical plane were measured using an Acoustic Doppler Veloci-meter (16 MHz Micro-ADV). The flow pattern around groynes was analyzed in both the horizontal and vertical planes. The results show that, for permeable groynes as the permeability increased the groyne length has limited influence on the flow structure. For the horizontal plane maximum and tip velocities were decreased while the minimum and bank velocities were increased as the permeability increased. Empirical formulas to describe these relations depending on the groyne relative length and permeability were suggested. The influence of permeable groynes installation in the compound channel has insignificant effect on the main channel flow while the impermeable groynes affect greatly the main channel flow structure. Both the groyne permeability and length ratio have obvious effects on the floodplain water depth.

Kajian stabilitas tumpukan batu dalam air

Abstract: Rock fill Dam, Coffer Dam, Groyne, Railway are example of structures composed by stone material. Rockfill structures are commonly stable enough, but when that’s constructed in under water, than stability ofstructure will decrease significant. Stability of stone structure under water actually depend on by somevariable these are depth of flooding, size or dimension, and stone position. The Author here will show withRail way stabilities calculation for example. Trial by two level position of flooding ,assume diameter stoneand gated value of properties , the result is stone with diameter 12 cm, will scour by less than 20 cm underwater. The Stone will scours by the flowing water if the velocity of water (Va) bigger than Critical velocityof the stone (Ucr). At the reality, rail way structured by stone with variation size more or less from 5 to 12cm, and depth of flooding possible occur more than 20 cm. So, rail way potential hanging cause of stonesupporting scour by flooding however only 10 cm depth. Calculation of stone stabilities used after Isbash,Goncharov,Levi dan Maynord formulae.